Association of Youth electronic cigarette USE with subsequent cigarette smoking Presented by Cathy L. Backinger, PhD, MPH Deputy Director for Research Office of Science

overview Youth Studies Young Adults Meta-Analysis and Recent Reports Summary No financial disclosures

Youth Studies

Study characteristics - Youth Authors Year of Study Start Place Age or Grade Study Length Leventhal, et al. (2015) 2013 10 Los Angeles public schools 9th graders (avg. 14.1) 12 months Wills, et al. (2016) Schools in Oahu, Hawaii 14-16 years Barrington-Trimis, et al. (2016) 2014 Southern California 11th &12th graders (avg. 17.4) 16 months Meich, et al. (2017) U.S. National 12th graders Connor et al. (2017) 20 U.K schools 13-14 years

Study characteristics - Youth Authors Year of Study Start Place Age or Grade Study Length Best et al. (2017) 2015 4 high schools Scotland 11-18 years 12 months Bold et al. (2017) 2013 3 public school in CT 13-17 years 24 months Treur et al. (2017) 19 secondary schools in Netherlands 11-17 years 6 months Hammond et al. (2017) 89 secondary schools in Ontario and Alberta, Canada Grades 9-12 Watkins et al. (2018) U.S. National 12-17 years

Measures - Youth Authors Sample of nonsmoking e-cig users Covariates in addition to age or grade, sex, race/ethnicity, tobacco use Leventhal, et al (2015) 222 - ever Family and peer smoking, depression, substance use, impulsivity, delinquent behavior, susceptibility Wills, et al (2016) 215 - ever Parent support, sensation seeking, rebellion, parental monitoring Barrington-Trimis, et al (2016) 146 – ever 94 - non-susceptible to smoking Friend smoking, friend influences, smoking susceptibility Meich, et al (2017) 54 - ever Binge drinking, marijuana use, risk for smoking, risk perceptions Connor et al. (2017) 343 - ever SES, school, smoking susceptibility, peer and family smoking status

Measures - Youth Authors Sample of nonsmoking e-cig users Covariates in addition to age or grade, sex, race/ethnicity Best et al. (2017) 183 – ever SES, smoking susceptibility, friends and family smoking, Bold et al. (2017) 72 - current SES, ever use of other tobacco products Treur et al. (2017) 61 – ever with nicotine 279 – ever without nicotine Education level, personality (anxiety, sensitivity, hopelessness, sensation seeking, impulsivity), susceptibility to peer pressure, smoking intention) Hammond, et al. (2017) 343 – current, not susceptible to smoking 412 – current, susceptible to smoking Smoking susceptibility, spending money Watkins et al. (2018) 425 – ever 87 - current Parental education level, urban residence, sensation seeking, alcohol use, live with a tobacco user, notice of warning labels, receptivity to tobacco advertising

Percent of current E-cigarette Use among 13-15 Year olds, GYTS Cigarette Smoking Among Youth E-Cigarette Users – longitudinal Studies Percent of current E-cigarette Use among 13-15 Year olds, GYTS OR 20 35 50 Odds Ratio of Ever E-Cigarette Use to Ever Cigarette Smoking at Follow-up Leventhal AM, et al. JAMA 2015 Wills TA, et al. Tob Control 2017 Barrington-Trimis JL, et al. Pediatrics 2016 Meich R et al. Tob Control 2017 Best C, et al. Tob Control 2017 Connor M, et al. Tob Control 2017 Treur JL, et al. European J Epi 2017 Watkins SL, et al. JAMA Ped 2018 * Among e-cig users not susceptible to cigarette smoking ** Relative risk

Percent of current E-cigarette Use among 13-15 Year olds, GYTS Cigarette Smoking Among Youth E-Cigarette Users – longitudinal Studies Percent of current E-cigarette Use among 13-15 Year olds, GYTS OR 20 22 Bold KW, et al. Pediatrics 2017 Hammond D, et al. CMAJ 2017 Watkins SL, et al. JAMA Ped 2018

Young Adults 6 studies (7 analyses) conducted since 2012 4 analyzed ever e-cigarette use to ever smoking 3 analyzed current e-cigarette use to current smoking 6-18 months follow-up Adjusted OR Ever to ever: 1.36 - 8.30 Current to current: one study: not significant, other two studies: 3.32 – 5.43

Meta-analysis and RECENT reports

Meta-analysis – youth and young adults Soneji S et al., JAMA Pediatrics, 2017 Pooled data from 7 longitudinal studies of youth and youth adults users that examined ever e-cigarette users compared with never e- cigarette users at baseline and ever cigarette smoking Adjusted for demographics, psychosocial and behavioral risk factors Pooled odds ratio: 3.62 (95% CI, 2.42-5.41) Data from 2 longitudinal studies of current (past 30-day use) cigarette smoking at follow-up among current e-cigarette user non- current cigarette smokers at baseline Pooled odds ratio: 4.28 (95% CI, 2.52-7.27)

Public Health Consequences of E-Cigarettes Report released January 23, 2018 Reviewed 10 studies of ever e- cigarette use to ever smoking: 6 youth, 4 young adults Reviewed 8 studies of e-cigarette use and subsequent risk of recent smoking/heavier smoking of cigarettes: 3 youth, 5 young adults *

Public Health Consequences of E-Cigarettes Conclusion 16-1: “There is substantial evidence that e-cigarette use increases risk of ever using combustible tobacco cigarettes among youth and young adults.” Substantial evidence: There are several supportive findings from good quality observational or controlled studies with very few or no credible opposing findings. A firm conclusion can be made, but minor limitations, including chance, bias, and confounding factors, cannot be ruled out with reasonable confidence. “Results were consistent across a number of methodologies, age ranges, research groups, and locations, and the associations were of considerable strength.”

Evidence review of e-cigarettes and heated tobacco products 2018 Use of e-cigarettes among young people; key findings: Despite some experimentation with these devices among never smokers, e-cigarettes are attracting very few young people who have never smoked into regular use Never smokers in the UK who try e- cigarettes are more likely to have tried smoking subsequently than those who have not tried e-cigarettes. A causal link has not been established and neither has progression to regular smoking.

Summary

summary Association of youth ever e-cigarette use with ever cigarette smoking 8 studies (10 analyses) conducted since 2013 with positive associations 6 -24 months Adjusted OR ranged from 1.75 to 11.9 Other youth associations 1 study (2 analyses) of current e-cig use to current cigarette smoking: adjusted OR: 3.87 to 7.08 2 studies (3 analyses) of ever e-cig use to current smoking, current e-cig use to ever smoking, and current e-cig use to past 7 days daily smoking: adjusted OR: 1.79 to 2.12 Young adult studies 6 studies (7 analyses) since 2012 - 6 with positive associations, one not significant

summary Meta-analysis and recent reports All studies Positive association for both youth and young adults ever e-cigarettes use to ever cigarette smoking All studies Variation in make-up of populations (age, race/ethnicity), geographic locations, tobacco use measures, covariates, and confidence intervals No studies have shown a protective effect of e-cigarette use preventing ever cigarette smoking among youth and young adults Does ever or current e-cigarette use lead to established smoking? Research will inform this question and to help understand mechanisms

Thank you

Factors to consider when assessing Youth E-cigarette use* Smoking and other tobacco use Peer use/influences Parent and family use/influences Intrapersonal, e.g., depression, anxiety, sensation-seeking Advertising Appeal, e.g., flavors, ease of use, cloud tricks Perceptions of health risks/effects Alcohol, marijuana, and other substance use Nicotine concentration * Not an exhaustive list